Question

State the work done in the following situation:

A man rowing a boat upstream at rest with respect to the shore.

Answer 1

Definition of work done

1. When a body moves through a certain distance under the effect of a force applied to it, work is said to be done on it. It is given as, $W=FS$, where, $F$ is force and $S$ is displacement

Explaining the amount of work done

1. The man applies force to row the boat across the stream.
2. A relative motion is produced between the boat and the stream.
3. Therefore, the man does work with respect to the stream.
4. However, the man is at rest with respect to the shore.
5. Since the displacement with respect to the shore is zero, work done with respect to the shore is also zero.

$$\begin{gathered} W=FS \\ W=F\times 0 \\ W=0 \end{gathered}$$

Therefore, the man does work with respect to the stream but no work is done with respect to the shore.